The cool airstream discharged from the condensing heat exchanger of an air cycle air conditioning system for aircraft, carries droplets of moisture which are generally removed by a water collector.
Unless the moisture is removed from the airstream, these droplets, when discharged into the cabin of the aircraft, create a foggy or misty atmosphere, or on occasion, freeze into ice. Further, system heat exchangers, turbines and ducting may be clogged by the buildup of ice, thereby reducing system efficiency and eroding system components.
Typically, the water to be removed is concentrated on the duct walls upstream from the water collector due to a type of centrifugal separation effected by the tortuous course the ducts follow. Therefore, that portion of the airstream closest to the duct walls carries the highest concentration of water. Prior art collectors have proven somewhat ineffective in removing this heavily moisture-laden air from the mainstream of the airflow.
One such prior art system employs a ring-like container around an annular gap in an air duct to collect the water moving on the duct walls. Since there is no outlet in the container, moisture-laden air fills the container, creating a higher pressure area therein, thereby forcing the water formed on the duct walls to cross the gap over the higher pressure air. While such a system may remove most of the water from a relatively slowly moving airstream (13.7 meters per second), it may not be capable of sufficiently drying a higher speed airstream (18.3 to 30.5 meters per second) typical of modern air cycle refrigeration systems. At such higher airflow speeds, a serial arrangement of several gaps and containers may be necessary to effectively dry the airstream, thereby rendering the system cumbersome.
The system disclosed in U.S. Pat. No. 3,834,126 granted to Philip J. Diminno, Jr. is an improvement to the above-noted prior art system. Like the abovenoted system, the Diminno, Jr. system has an annular gap provided in an air duct and surrounded by a container to collect the water moving on the duct walls. However, the Diminno, Jr. system also employs vent tubes between the duct and the container, upstream of the gap to lower the air pressure in the container, thereby inducing the airflow and water to travel therethrough. However, in certain applications, airflow through the container may not be sufficient to inhibit the water from crossing the gap. Indeed, this patent indicates that water droplets may be carried beyond the gap, risking the retention of excessive, unwanted water in the airstream.
Accordingly, a high performance water collector of enhanced efficiency, for extracting water from a high speed airstream exhausted from an air cycle refrigeration system turbine, is desirable.